A circuit board, such as a printed circuit board, may be comprised of one or more components, such as high density LSI's, which generate a significant amount of heat during operation. To keep these components from overheating, a cooling system is often employed to cool the components. With such a cooling system, several circuit boards may be densely installed in a small space.
FIGS. 1A, 1B and 1C illustrate a typical cooling system 10. The cooling system 10 includes a housing 12 that is mounted on both sides of a circuit board 14. The cooling system 10 also includes an inlet 16 and an outlet 18, which allow a coolant to enter and exit the housing 12 to cool the circuit board 14.
The housing 12 has an open side face 20 on which the circuit board 14 is mounted. The housing 12 and circuit board 14 form an enclosed chamber for receiving a coolant. When the coolant is in the chamber, it cools the circuit board 14. The housing 12 has a flange 22 on which the circuit board 14 is sealingly attached using screws 24 or using bolts and nuts. Typically, an O-ring seal 25 is placed in a groove (not shown) on the face of the housing flange 22. When the circuit board 14 is mounted on the face of the housing flange 22, the O-ring seal 25 is compressed against a smooth surface of the circuit board 14 to seal the gap between the housing flange 22 and the circuit board 14. The smooth surface of the circuit board 14 is generally provided by a metallic sheet that is attached to the circuit board by, for example, screws (not shown).
In some cases, only one side of a circuit board may be attached to a housing so that only one side of the circuit board comes in contact with the coolant. The housing may be attached to the circuit board in the manner shown in FIGS. 1A, 1B and 1C.
The prior art cooling system 10 shown in FIGS. 1A, 1B and 1C has several disadvantages. First, the connectors 26 of the circuit board 14 are not cooled by the cooling system 10. Because the housing 12 of the cooling system 10 is attached to a side of the circuit board 14, the connectors 26 of the circuit board 14 are outside of the housing 12 of the cooling system 10. Since the connectors 26 of the circuit board 14 generate considerable heat, not cooling the connectors 26 is a significant disadvantage. Second, because of the need for space on the circuit board 14 to accommodate the smooth surface for the O-ring seal, a circuit board with the smooth surface is made larger. In addition, the circuit board 14 must have space to accommodate the screws 24 for attaching the housing 12 to the circuit board 14, further increasing the size of the circuit board 14. Third, the O-ring circles the entire open face 20 of the housing 12 and thus is longer and more prone to leakage.